If you had the personal vault setup and working before, and it disapeared after an update or when you re-synched OneDrive, here is how you can bring it back:
- Go to OneDrive synched folder.
- Create a new shortcut
- Paste the following as shortcut location:
odopen://unlockVault/?accounttype=personal
- Rename to 'Personal Vault - Custom'
- Save
This new shortcut can now be used to access Personal Vault.